Sheet feeder apparatus

ABSTRACT

A feeder apparatus includes a feed tray for stacking documents, a document detection sensor for detecting the documents on the feed tray, a supply roller for contacting a top surface of the documents on the feed tray and supplying the documents, and a support plate disposed in front of the feed tray for supporting a leading edge of the documents in a feed direction and being able to rise and fall between a lower limit position where the documents are loaded on the feed tray and an upper limit position where the top surface of the documents contacts the supply roller. The support plate is controlled to wait at a standby position below the upper limit position after the documents are loaded on the feed tray and move from the standby position to the upper limit position upon receiving a feed signal to start feeding the documents.

1. BACKGROUND OF THE INVENTION

[0001] The present invention relates to a feeder apparatus that suppliessheets loaded in a feed tray one at a time to a predetermined processingposition, and in particular to a feeder apparatus equipped with a riseand lower tray that can rise and fall upward and downward so that thesheets on the feed tray can make contact with a supply means to besupplied.

2. RELATED ART STATEMENT

[0002] It is desirable that a feeder apparatus used in copying machines,facsimiles, printers and document feeding apparatuses can handle agreater number of sheets at one time as possible.

[0003] A feed tray where the sheets are loaded in an ADF that handlesthis type of thick bundle of sheets becomes deeper. However, in an ADFcomprised such that the sheets are sequentially supplied from theuppermost position one sheet at a time, a supply position of the sheetswill vary largely between when there is one sheet and when there are 100sheets loaded on the feed tray, thereby creating a large gap to a feedpath located at a fixed position. Thus, it is hindered to supply thesheet smoothly, thereby increasing a risk of paper jams.

[0004] Consequently, in order to reduce an influence of the number ofthe sheets loaded in a feed tray, there have been utilized conventionalfeeder apparatuses equipped with rise and lower trays that can rise andfall upward and downward for allowing a position of the sheet bundle torise and fall in response to the position of a surface of the uppermostsheet. As an example of this type of conventional technology, JapanesePatent Publication (Tokkai) No. 09-166831 disclosed an apparatus thatelevates a sheet lifting member for supplying the sheets held in holdingmeans one by one when the sheet feed starts, and then allows the sheetlifting member to lower when the trailing edge of the last sheet in theholding means passes through the sending means.

[0005] In this conventional technology, when the feed command isreceived by pressing the read start button (start button) located on aside of a main image reading apparatus, the apparatus is controlled suchthat a support plate is raised from the lower limit position up to aposition (upper limit position) where the uppermost sheet loaded on thefeed tray reaches the supply position to contact a supply roller basedon a sheet detection signal that a sheet sensor (hereinafter referred toas an empty sensor) detects the sheets loaded on the feed tray.

[0006] The support plate is controlled to rise in response to areduction in an amount of the sheets supplied from the feed tray so thatthe supply roller always contacts the uppermost sheet, and to lower tothe lower limit position located as an initial standby position when theempty sensor detects that all the sheets on the feed tray have beensupplied.

[0007] In a feeder apparatus having the support plate controlled in thismanner, there is little problem when a large number of document sheetsare loaded on the feed tray (thick bundle of the sheets). However, whenthe number of the sheets is small, the support plate must move upward along distance from a location close to the lower limit position up tothe upper limit position at the highest position. Therefore, it takes along time for the support plate to move to the position where theuppermost sheet is supplied after an operator presses the read startbutton (start button). In this case, the operator might suspectsomething wrong since the sheet feed does not start after the operatorpressed the start button, and practically, the sheet read time requiresa long time when the number of the sheets is small.

OBJECTS OF THE INVENTION

[0008] To solve the problems related to the conventional technology, thefirst object of the invention is to provide a feeder apparatus that cangreatly shorten time to supply the uppermost sheet regardless of theamount of the sheets loaded on the feed tray.

[0009] The second object is to provide a feeder apparatus that canreduce the time to supply the uppermost sheet after receiving a feedsignal as well as a feeder apparatus that can easily remove the loadedsheets all at once.

SUMMARY OF THE INVENTION

[0010] A feeder apparatus is equipped with stacking means for supportingan edge of a sheet on a feed tray and being able to rise and fallbetween a lower limit position for loading the sheets onto the feed trayand an upper limit position for allowing a top surface of the sheets tocontact supplying means.

[0011] When an empty sensor S1 detects the sheet before a feed signal isreceived to start sheet feeding, the stacking means is controlled torise to a predetermined sheet supply position in advance, and the sheetis supplied when the feed signal is received, thereby taking shortertime to supply the uppermost sheet after receiving the feed signal.

[0012] In addition, when the sheet is detected on the stacking meansbefore a feed signal is received to start sheet feeding, the stackingmeans is controlled to rise to a standby position in advance, and tomove from the standby position to a predetermined sheet supply positionwhere the sheet is supplied when the feed signal is received, therebytaking shorter time to supply the uppermost sheet after receiving thefeed signal. It is also easy to remove the loaded sheets all at once.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a view showing an entire configuration of an automaticdocument feeding apparatus to which a feeder apparatus of the presentinvention is applied;

[0014]FIG. 2 is a view showing main components of the automatic documentfeeding apparatus to which the feeder apparatus of the present inventionis applied;

[0015]FIG. 3 is a control block diagram according to the presentinvention;

[0016]FIG. 4 is a view showing a raise and lower mechanism of a supportplate according to the present invention;

[0017]FIG. 5 is a flowchart showing a rise and fall operation of thesupport plate according to the present invention;

[0018]FIG. 6 is a flowchart showing the rise and fall operation of thesupport plate according to the present invention;

[0019]FIG. 7 is a view showing a state in which the support plateaccording to the present invention is located at a lower limit position;

[0020]FIG. 8 is a view showing a state in which the support plateaccording to the present invention is located at an upper limitposition;

[0021]FIG. 9 is a view showing a state in which the support plateaccording to the present invention is located at a standby position;

[0022]FIG. 10 is a view showing a state in which the document on thesupport plate according to the present invention is fed completely;

[0023]FIG. 11 is a flowchart showing the rise and fall operation of thesupport plate in a modified example according to the present invention;and

[0024]FIG. 12 is a flowchart showing the rise and fall operation of thesupport plate in a modified example according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0025] Embodiments of the feeder apparatus related to the presentinvention will be described in detail based on an automatic documentfeeding apparatus whereon the feeder apparatus of the present inventionis applied.

[0026]FIG. 1 shows the overall composition of an automatic documentfeeding apparatus equipped with a feeder apparatus installed on theimage reading apparatus. FIG. 2 is an expanded view of the principalcomponents of the automatic document feeding apparatus.

[0027] Looking at FIG. 1, A is the automatic document feeding apparatusinstalled on the image reading apparatus H. The automatic documentfeeding apparatus A transports documents in a manner such that they passover the contact glass surface 1 a of the main unit H.

[0028] The main unit H reads document images by illuminating thedocument that is transported by a light from the light source 2, such asa lamp, through the first contact glass 1 a, reflecting this reflectedlight by the mirror 3 and then photoelectrically converting the lightusing the reading means 5 (such as a CCD) through the lens 4.Consequently, the upper surface of the first contact glass 1 a comprisesthe reading components of the main unit H. The main unit H is alsoequipped with the second contact glass 1 b that has a surface area ontowhich documents can be loaded. The main unit H can read images ofdocuments through the second contact glass 1 b by means of opening andclosing the automatic document feeding apparatus A and moving a lightsource unit, formed from the light source 2 or mirror 3, in a verticalscanning direction over thick documents, such a books, loaded onto thecontact glass 1 b.

[0029] Next, the composition of the automatic document feeding apparatusA will be described referring to FIG. 1 and FIG. 2.

[0030] The automatic document feeding apparatus A comprises the feedtray 10 that functions as a stacking means whereon a plurality ofdocuments can be loaded, the support plate 22 that loads a plurality ofdocuments and rises upward and falls downward to a supply position, andthe first delivery tray 18 and second delivery tray 19 which function asa storage means to store the read documents. The first delivery tray 18mainly stores large-sized documents and the second delivery tray 19stores small-sized documents. The descriptive number 20 in FIG. 1 is apush-up lever comprised by a porous member, such as a sponge, and a filmmember, such as white Mylar. This push-up lever 20 functions to push thesecond contact glass 1 b upward.

[0031] In addition, the automatic document feeding apparatus A has thefeed path 11 that feeds documents located on the feed tray towards thesecond contact glass 1 b one sheet at-a-time, the transport path 12,formed coupled to the feed path 11, that guides documents along theupper surface of the first contact glass 1 a, and the first deliverypath 13 coupled from the transport path 12 to the delivery opening ofthe first delivery tray 18. The automatic document feeding apparatus Aalso has the circulation path 14 connected from the delivery opening ofthe first delivery tray 18 to the connecting portion between the feedpath 11 and the transport path 12 that returns documents to thetransport path 12, the middle path 15, formed branching off from thefirst delivery path 13, that guides documents from the transport path12, and the second delivery path 16 coupled from the middle path 15 tothe delivery opening of the second delivery tray 19. The document pathis comprised of the switchback path 17 a, formed branching off from thesecond delivery path 16, that allows documents to switch back from themiddle path 15 and the reverse path 17 b that reverses that front andback side of the documents which were switched back and guides them tothe delivery opening of the second delivery tray 19.

[0032] The sides of the documents loaded on the feed tray 10 arecontrolled by the side guard 20 and the edges of the documents arefurther controlled by the stopper barrier 21. The feed tray 10 ismounted so it can rotate with the side of the document in the directionof the feed acting as a fulcrum.

[0033] Various devices are arranged on the feed path 11; the supplyroller 23 that supplies documents, the rise and lower tray (hereinafterreferred to as the support plate 22) that raises the edge of thedocuments loaded on the feed tray 10 allowing it to make contact withthe supply roller 23, the rise and fall lever 49 raises and lowers thesupport plate 22, the separation means comprising the feed roller 24that feeds documents supplied by the supply roller 23 and the separationmember 25 that only allows the first document at the highest position topass and hinders the feed of the documents after the second sheet, andthe pair of resistance rollers 26 which send documents to the lower flowlevel in the apparatus after the edges of the documents which areseparated into individual sheets by the separation means and fed, arestraightened out.

[0034] The supply roller 23 and the feed roller 24 are coupled to anddriven by the feed motor M1 through the one-way clutch OW1. The pair ofresistance rollers 26 are also coupled to and driven by the feed motorM1 through the one-way clutch OW2. This linkage drives the supply roller23 and the feed roller 24 by the forward turning of the feed motor M1.The pair of resistance rollers 26 is driven by the reverse turning ofthe motor.

[0035] The plurality of driven rollers 28, 29 and 30 are arranged in thetransport path 12. These driven rollers 28, 29 and 30 press against thelarge diameter transport roller 27 and the peripheral surface of thetransport roller 27. The transport roller 27 is comprised so as to bedriven by the transport motor M2.

[0036] The driven roller 31 and the pair of first delivery rollers 32are arranged in the first delivery path 13. The driven roller 31 pressesagainst the transport roller 27 and the pair of first delivery rollers32 deliver documents to the first delivery tray 18. The pair of firstdelivery rollers 32 is coupled to the first reverse delivery motor M3that can rotate forward and reverse. They are controlled such that theback edge of the document turns in reverse in a nipped state indouble-side mode, the document switches back and then is sent to thetransport path 12 through the circulation path 14. In addition, the pairof first delivery rollers 32 are comprised such that one of the rollers32 a separates from the other roller 32 b by means of the pressuresolenoid SOL1 that allows document transport without any impedimentswhen the leading edge of the documents are shifting differently as theycirculate through the circulation path 14 and the transport path 12.

[0037] The pair of middle rollers 33 is arranged in the middle path 15.This pair of middle rollers 33 sends documents to the lower flow level.The pair of second delivery rollers 35 are arranged in the seconddelivery path 16. The pair of second delivery rollers 35 deliversdocuments to the second delivery tray 19. Furthermore, the pair ofswitchback rollers 34 are arranged in the switchback path 17 a. The pairof switchback rollers 34 allows documents to switchback and then sendthe documents to the pair of second delivery rollers 35 through thereverse path 17 b.

[0038] The pair of middle rollers 33 are driven by the first reversedelivery motor M3 and the pair of second delivery rollers 35 and thepair of switchback rollers 34 are driven by the second reverse deliverymotor M4 that can turn forward and reverse.

[0039] The first flapper 40 is disposed in the lower flow side of thetransport path 12 and functions to guide documents to either the firstdelivery path 13 or the middle path 15. The second flapper 41 is alsodisposed in the lower flow side of the middle path 15 and functions toguide documents to either the second delivery path 16 or the switchbackpath 17 a. These two first and second flappers are movable by means ofthe first solenoid SOL2 and the second solenoid SOL3, respectively. Theempty weight flappers 42, 43 are disposed in the first delivery path 13and the switchback path 17 a. These flappers 42, 43 are movable in theupward direction by means of the leading edge of the documents which aresent and allow the documents to pass through. When the trailing edge ofthe documents pass through the flippers, they are movable in thedownward direction.

[0040] The empty sensor S1 is disposed in the document feed directionlower flow side of the feed tray 10. This sensor detects whetherdocuments are loaded on the feed tray 10. The length sensor S2 and theresistance sensor S3 are disposed on the feed path 11. These sensorsdetect the edge of the documents being fed. The lead sensor S4 isdisposed in front of the first contact glass 1 a. The first dischargesensor S5 is disposed at the delivery opening of the delivery tray 18.The center sensor S6 is disposed in the middle path 15. The seconddelivery sensor S7 is disposed close to the delivery opening of thesecond feed tray 19. The switchback sensor S8 is disposed in theswitchback path 17 a. These sensors detect the edge of the documentsbeing sent. The upper limit sensor S9 and the lower limit sensor S10 aredisposed close to the feed opening of the feed path 11. The upper limitsensor S9 detects whether the support plate 22 is located at the upperlimit position where the document surface at the highest position makescontact with the supply roller 23. The lower limit sensor S10 detectswhether the support plate is located at the lower limit position wherethe document can be loaded.

[0041] As shown in FIG. 3, the above-mentioned sensors S1 to S10 areconnected to the control assembly 55 that functions as a control meansand contains a CPU. The control assembly 55 controls the transport ofthe documents. Each of the above-mentioned motors M1, M2, M3, M4 andeach solenoid SOL1, SOL2 and SOL3 are controlled based on output signalsfrom each sensor and then a send operation of documents is executed.

[0042] The control assembly 55 that functions as a control means(described later) controls the rise and fall motor M5 based on outputsignals from the empty sensor S1, the upper limit detection sensor S9and the lower limit detection sensor S10 as well as feed signals fromthe main unit H. Thereafter, the rise and fall operation of the supportplate 22 executes.

[0043] Next, the document send operation of the automatic documentfeeding apparatus with the above composition will be described.

[0044] At first, the single-side mode that reads one side of thedocument will be described. When a feed signal (feed command) isreceived from the main unit H with the empty sensor S1 in an ON state,in other words, the sensor detects that a document is loaded on the feedtray, the support plate 22 is controlled to rise and fall until thedocument at the highest position makes contact with the supply roller23.

[0045] The rise and fall control of the support plate will be describedin detail afterward.

[0046] The feed motor M1 starts turning forward. This turning actionturns the supply roller 23 and the feed roller 24 sending the documentson the feed tray. At this time the supply roller 23 and the feed roller24 are turned in the document send direction although the pair ofresistance rollers 26 do not turn due to the function of the one-wayclutch OW2. Then when the resistance sensor S3 detects the leading edgesof the documents being fed, the feed motor M1 is stopped once after thedocuments are transported a predetermined amount from the moment theleading edge is detected. At this time the leading edges of thedocuments are pushed against the nip portion of the pair of resistancerollers 26 and are formed into a arc shape. This aligns the leadingedges of the documents and eliminates skewing. After the feed motor M1stops once, it is driven in reverse and the documents are fed from thefeed path 11 to the transport path 12.

[0047] The transport motor M2 is driven simultaneously with the reverseturning drive of the feed motor M1 resulting in the documentstransported on the feed path 11 being transported along the transportroller 27. Then, when the leading edges of the documents transported inthe transport path 12 are detected by the lead sensor S4, the documentsare then transported a predetermined amount and the feed motor M1 andthe transport motor M2 are stopped. At this time the documents stop at aposition in front of the first contact glass 1 a. Then, when theread/transport signal is received from the main unit H, the transportmotor M2 drives again allowing the documents to pass over the firstcontact glass 1 a. While the documents pass over the glass the frontsurface of the documents are read by the reading means.

[0048] Next, the send operation for the documents is selected dependingon the subsequent document size.

[0049] When the documents are long, the first solenoid magnetizes andmoves to a position guiding the first flapper 40 to the first deliverytray 18 along with the first reverse delivery motor M3 driving in theforward direction turning the pair of first delivery rollers 32 forward.This action discharges documents which have passed over the firstcontact glass 1 a by means of the transport roller 27 to the firstdelivery tray 18 along the first delivery path 13 from the documentfeed.

[0050] When the documents are short, the first flapper 40 is held at itsposition where it is guided to the middle path 15 and the first reversedelivery motor M3 drives in the forward direction turning the middlerollers 33. This action guides documents which have passed over thefirst contact glass 1 a and discharges them to the second delivery tray19 through the second delivery path 16 by means of the middle rollers 33and the pair of second delivery rollers 35.

[0051] Next, the double-side mode in which both surfaces of the documentare read will be described. In double-side mode, the document feed andtransport operation from the feed tray 10 to the position in front ofthe first contact glass 1 a are controlled identical to the documentfeed and transport operation of the single-side mode.

[0052] When a read transport signal is received from the main unit H,the transport motor M2 turns and the first delivery motor M3 turnsforward. By means of this action the front surface of the document isread by the read means in a process in which the document passes overthe first contact glass 1 a. At this time, for double-side more, thefirst solenoid magnetizes and moves to a position guiding the firstflapper to the first delivery path 13 irregardless of the length of thedocument. The document whose front surface is read by this action isguided to the first delivery path 13.

[0053] The edge of the document guided to the first delivery path 13presses upward on the third flapper 42 arranged such that the firstdelivery path 13 is blocked and is then transported to the delivery tray18. Then, when the first delivery sensor S5 detects the trailing edge ofthe document, the first delivery motor M3 and the transport motor M2 arestopped. When they stop, the trailing edge of the document is nipped bythe pair of delivery rollers 24 and the leading edge is exposed on thefirst delivery tray 18. Thereafter, the first delivery motor M3 isdriven in reverse. This action turns the pair of first delivery rollers32 in reverse switching back the document and guiding it in thecirculation path 14 along the document guiding surface of the thirdflapper 42.

[0054] The leading edge of the document switched back by the pair offirst delivery rollers 32 transports a predetermined amount after beingdetected by the first delivery sensor S5. Because of this, the leadingedge of the document is pushed against the nip portion of the transportroller 27 in a stopped state and the driven roller 28 that is pressingagainst the transport roller 27 forming the leading edge into an arcshape. This eliminates skewing.

[0055] The transport motor M2 drives again to re-supply a document andthe transport roller 27 is turned. The document is transported followingthe transport roller 27 and when the leading edge of the document isdetected by the lead sensor S4, the transport motor M2 stops after apredetermined time.

[0056] In other words, the document whose leading edge is sent to thefirst delivery tray 18 is returned to the transport path 12 againthrough the circulation path 14 by the first delivery rollers 32.

[0057] Then, when the read/transport signal is received from the mainunit H, the transport motor M2 drives again and the first delivery motorM3 turn forward. Because of this, the rear surface of the document isread by the reading means in a process in which the document passes overthe first contact glass 1 a.

[0058] Hereupon, depending on the document size there are differentoperations to control the first flapper 40, switch the path that guidesthe document and then finally discharge the document.

[0059] If the size of the document is long, the first flapper 40 movesto a position where the document is guided to the first delivery path13. The document is then guided to the first delivery path 13 and isreturned to the transport path 12 again through the circulation path 14in order to line up the pages. Then, the document passes over the firstcontact glass 1 a and is delivered to the delivery tray 18 from thefirst delivery path 13.

[0060] If the size of the document is short, the magnetization of thefirst flapper 40 is released. The flapper moves to a position guidingthe document to the middle path 15 and then the document is guided fromthe middle path 15 to the switchback path 17 a. After the document isswitched back by the switchback path 17 a, it is reversed by the reversepath 17 b and delivered to the second delivery tray 19.

[0061] The raise and lower mechanism and the rise and fall operation ofthe support plate 22 will be described now.

[0062]FIG. 4 shows the raise and lower mechanism that raises and lowersthe support plate 22 in the document supply assembly of the apparatus.FIG. 4(a) is a perspective view looking at the control mechanism fromthe top and FIG. 4(b) is a compositional example looking at the controlmechanism from the bottom.

[0063] The control mechanism of the support plate 22 in this embodimentis comprised by the support plate 22 that loads and raises and lowersdocuments, the rotating support point shaft 53 that is mounted to theapparatus frame and functions to rotate and raise and lower the supportplate 22, the rise and fall lever 48 that makes contact with the loweredge of the surface of the support plate 22 in the document transportdirection and raises and lowers the support plate 22, the rotating shaft51 that is coupled to the rise and fall lever 48 and allows the rise andfall lever 48 to rotate, the rise and fall motor M5 that can rotateforward and allows the rotating shaft 51 to rotate, and the plurality ofgears 52 which transfer the driving force of the rise and fall motor M5to the rotating shaft 51.

[0064] According to this composition, when the rise and fall motor M5turns forward, the support plate 22 transfers the driving force of themotor to the rotating shaft 51 by way of the plurality of gears 52thereby turning the rotating shaft 51 upward. Then, the turning of theaction of the rotating shaft 51 turns the rise and fall lever 48 whichmakes contact with the lower surface of the support plate 22. The leverpresses against the support plate 22 raising it upward.

[0065] When the rise and fall motor M5 turns in reverse, the rotatingshaft 51 turns downward by way of the gears 52. This action lowers therise and fall lever 48 releasing the support of the rise and fall lever48 allowing the support plate 22 to fall by its own weight.

[0066] This raise and lower mechanism is equipped with the lower limitdetection means that detects whether the support plate 22 is located ata position where the document can be loaded, and an upper limitdetection means that detects whether the document at the highestposition on the support plate 22 is making contact with the supplyroller 23.

[0067] The lower limit detection means has the lower limit sensor lever48 coupled to the support lever 22 and the light emitting assembly andthe light receiving assembly. The lower limit detection means iscomprised by the concave lower limit sensor S10 formed such that itblocks light from the light emitting assembly to the light receivingassembly by means of the lower limit sensor lever 48 entering into it.The upper limit detection means has the upper limit sensor lever 47formed on the bracket of the supply roller 23 and the light emittingassembly and the light receiving assembly. The upper limit detectionmeans is comprised by the concave upper limit sensor S9 formed such thatit blocks light from the light emitting assembly to the light receivingassembly by means of the upper limit sensor lever 48 entering into it.

[0068] The rise and fall motor M5 is controlled by means of thedetection results of this lower limit detection means and upper limitdetection means raising and lowering the support plate 22 to the upperlimit position and the lower limit position.

[0069] The upper limit position of the support plate 22 mentioned aboveis a position where the surface of the document at the highest positionon the support plate 22 makes contact with the supply roller 23. Inaddition, the upper limit position of the support plate 22 is a positionthat changes depending on the amount of documents loaded. The lowerlimit position of the support plate 22 is a position where document canbe loaded onto the support plate 22.

[0070] Next, the rise and fall operation of the support plate 22 will bedescribed based on the control block diagram shown in FIG. 3, the riseand fall control flowchart of the support plate 22 shown in FIG. 5 toFIG. 6 and the state diagrams shown in FIG. 7 to FIG. 10.

[0071] As shown in FIG. 6, when the document is loaded onto the feedtray 10 and the support plate 22 while the support plate 22 is locatedat the lower limit position, the loaded document will be detected by theempty sensor S1 (ST1). The rise and fall motor M5 turns forward (ST3)after a predetermined time T1 passes (ST2) from the time when the emptysensor S1 detects the document. This action raises the rise and fallplate 22.

[0072] Here, the predetermined time T1 is a time required for theoperator to load the document at a suitable position. This eliminatesthe support plate 22 from rising up suddenly while stacking document aswell as making it possible to securely stack documents at a suitableposition on the feed tray thereby eliminating any apprehension operatorsmay have.

[0073] The surface of the document at the highest position makes contactwith the supply roller 23, as shown in FIG. 8, by means of the risingsupport plate 22 gradually raising up the documents. The upper limitsensor will turn ON when the surface of the document at the highestposition rises up to the position where it makes contact with the supplyroller 23 (ST4). The support plate 22 reaching the upper limit positionis detected by this.

[0074] When the upper limit sensor S9 detects that the support plate 22has reached the upper limit position, the rise and fall motor M5 willstop one (ST5). Thereafter, the rise and fall motor M5 turns in reverseand the support plate 22 is lowered by a predetermined amount L andstops (ST6 to ST8). At this time, the support plate 22 is in a standbystate lowered by only a predetermined amount C as shown in FIG. 9.

[0075] Hereupon, the above-mentioned predetermined amount C is an amountdetermined in advance that lowers the surface of the document at thehighest position to a position where it does not make contact with thesupply roller 23.

[0076] Because the support plate 22 lowers the surface of the documentat the highest position to a position where it does not make contactwith the supply roller 23 and waits in a standby state in this manner,the operator can easily remove documents from the feed tray 10 withoutaffecting the supply roller 23.

[0077] When the feed signal is received from the main unit H within thepredetermined time T2 after the support plate 22 is lowered to thestandby position, the rise and fall motor M5 will turn forward again andthe support plate 22 will rise up from the standby position (ST9 toST11). In addition, when the upper limit sensor S9 detects that therising support plate has reached the upper limit position, the rise andfall motor M5 will stop (ST12 to ST13). At this time, the surface of thedocument at the highest position is brought into contact with the supplyroller 23 as shown in FIG. 8.

[0078] Thereafter, the feed motor M1 turns forward driving the feedroller 24 and supplying documents. Subsequently, the document feedoperation described above is executed (ST14).

[0079] When the feed signal is received from the main unit H within thepredetermined time T2 after the support plate 22 is lowered to thestandby position, the rise and fall motor will turn in reverse again andthe support plate 22 will lower down (ST9, ST15). When the lower limitsensor S10 detects that the support plate 22, lowering down from thestandby position, has reached the lower limit position, the rise andfall motor M5 will stop (ST16 to ST17). Thereafter, when the feed signalis received from the main unit H (ST18), the normal document feedoperation will execute (ST11 to ST14) wherein the rise and fall motor M5immediately turns forward raising the support plate 22 from the lowerlimit position to the upper limit position and driving the supply roller23 and the feed roller 24.

[0080] Then, as shown in FIG. 10, all the documents on the feed tray 10are fed by means of the document feed operation. When the empty sensorS1 detects that there are no more documents on the feed tray, the riseand fall motor M5 immediately turns in reverse and the support plate 22is controlled lowering down to the lower limit position.

[0081] When the feed signal is received from the main unit H within thepredetermined time T2 with the support plate 22 at the standby positionin this manner, the fact that the support plate 22 is lowered down tothe lower limit position makes it possible to reduce the electricalpower consumption because it is not necessary to supply a holdingcurrent to the rise and fall motor M5.

[0082] Furthermore, the support plate 22 is controlled so as to beforcefully raised up to the upper limit position where the document feedoperation executes when the feed signal is received during theabove-mentioned rise and fall operation.

[0083] Even further, the support plate 22 is controlled so as toimmediately lower down to the lower limit position when the empty sensorS1 detects that there are no documents due to, for example, thedocuments being removed.

[0084] Describing the above-mentioned embodiment in more detail, whenthe empty sensor S1 detects a document before the feed signal from themain unit H is received, the support plate 22 will rise up to thestandby position in advance and then rise from the standby position upto the upper limit position in order to supply the documents at themoment when the feed signal is received from the main unit H.Consequently, it is possible to greatly shorten the time until thedocument at the highest position is supplied irregardless of the amountof documents loaded on the feed tray.

[0085] In the above-mentioned embodiment, control is such that when therise and fall support pate 22 to the standby position is moved, it risesuntil it is detected once by the upper limit sensor S9. Thereafter, therise and fall support pate 22 lowers down a predetermined amount and thestandby position is made a position as close as possible to the supplyroller. However, after taking into consideration the maximum amount ofdocument that can be loaded, it is also possible to arrange the sensorat a suitable position between the lower limit position and the upperlimit position and then use the sensor to detect and wait for thesupport plate 22.

[0086] Next, a modified example of the rise and fall control of thesupport plate 22 will be described below.

[0087] In the above-mentioned embodiment, if we take into considerationremoving the documents from the feed tray 10 after stacking them onetime on the feed tray 10, setting the standby position and removing thedocuments is easier. In this modified example however, as shown in therise and fall control flowchart of FIG. 10 to FIG. 11 control is suchthat the document detection performed by the empty sensor S1 allows thesupport plate 22 to be raised from the lower limit position, where thedocuments are loaded, up to the upper limit position in order to supplythe documents (ST20 to ST24) thereafter driving the supply roller at themoment when the feed signal is received from the main unit H. This makesit possible to shorten the time even more than the document supply timein the above-mentioned embodiment.

[0088] In addition, in the rise and fall operation of the modifiedexample, control is such that when the feed signal is not received eventhough the predetermined time has elapsed after the support plate risesfrom the lower limit position to the upper limit position in order tosupply the documents, the support plate will lower and return to thelower limit position (ST25 to ST30). Because of this, an effect can beobtained that makes it possible to reduce the electrical powerconsumption in like manner to the above-mentioned embodiment.

What is claimed is:
 1. A feeder apparatus for sequentially feedingsheets to a predetermined processing position, comprising: stackingmeans for stacking the sheets, supply means for contacting a surface ofan uppermost sheet stacked in the stacking means and for supplying thesheet, raise and lower means for raising and lowering the stacking meansbetween a lower limit position for stacking the sheets and an upperlimit position for allowing the surface of the uppermost sheet tocontact the supply means, sheet detection means for detecting the sheetsstacked in the stacking means, and control means for controlling theraise and lower means to move the stacking means from the lower limitposition to the upper limit position upon receiving a detection signalof the sheet detection means, and for controlling the supply means todrive upon receiving a feed signal that directs to start feeding thesheets.
 2. A feeder apparatus according to claim 1, wherein saidstacking means comprises a feed tray for supporting a trailing edge ofthe sheet in a feed direction, and an rise and lower tray for supportinga leading edge of the sheet in the feed direction, said raise and lowermeans raising and lowering the rise and lower tray.
 3. A feederapparatus according to claim 1, wherein said control means controls theraise and lower means so that the rise and lower tray moves to the lowerlimit position when there is no feed signal after a predetermined timeafter the rise and lower tray moves to the upper limit position.
 4. Afeeder apparatus for sequentially feeding sheets to a predeterminedprocessing position, comprising: stacking means for stacking the sheets,supply means for contacting a surface of an uppermost sheet stacked inthe stacking means and for supplying the sheet, raise and lower meansfor raising and lowering the stacking means between a lower limitposition for stacking the sheets, an upper limit position for allowingthe surface of the uppermost sheet to contact the supply means, and astandby position disposed between the lower limit position and the upperlimit position, sheet detection means for detecting the sheets stackedin the stacking means, and control means for controlling the raise andlower means to move the stacking means from the lower limit position tothe standby position to standby based on a detection result of thedetection means, and to move the stacking means from the standbyposition to the upper limit position upon receiving a feed signal thatdirects to start feeding the sheets.
 5. A feeder apparatus according toclaim 4, wherein said stacking means comprises a feed tray forsupporting a trailing edge of the sheet in a feed direction, and an riseand lower tray for supporting a leading edge of the sheet in the feeddirection, said raise and lower means raising and lowering the rise andlower tray.
 6. A feeder apparatus according to claim 5, wherein saidcontrol means controls the raise and lower means so that the rise andlower tray moves to the lower limit position when there is no feedsignal after a predetermined time after the rise and lower tray moves tothe standby position.
 7. A feeder apparatus according to claim 5,further comprising lower limit detection means for detecting whether therise and lower tray is located at the lower limit position, and upperlimit detection means for detecting whether the surface of the uppermostsheet on the rise and lower tray contacts the supply means.
 8. A feederapparatus according to claim 7, wherein said control means controls theraise and lower means to raise the rise and lower tray from the lowerlimit position upon receiving the detection signal of the sheetdetection means, and to lower the rise and lower tray by a predeterminedamount and move the rise and lower tray to the standby position when theupper limit detection means detects the surface of the uppermost sheet.9. A feeder apparatus according to claim 5, wherein said control meanscontrols the raise and lower means to start moving from the lower limitposition to the standby position after a predetermined time from whenthe detection means detects the sheets stacked in the feed tray.